The structural and kinetic interactions of calcium phosphate salts with hard tissue matrix macromolecules and metabolites is being studied by a number of techniques including infrared, laser Raman and magnetic resonance spectroscopy and x-ray diffraction. In addition, quantitative diffraction procedures are used to assay bone maturation, degeneration and recovery in experimental disease states, such as chronic uremia and tetracycline toxicity, with emphasis placed on the effectiveness of potential therapeutic agents. Tooth protein development and structure are being investigated as well as their ongoing entropic, electrostatic and three-dimensional influences on crystal formation in biological systems.